Thanks for the reply, SeaMonkey. I see that some of your proposals in the "New Features" thread deal with this and related issues a bit.
At the corps and army level, one per hex makes sense, and I accept the rationale that armored elements are integral to the infantry formations.
But the engineers and special forces seem like they could share the space with a larger formation.
With respect to tank groups--are these supposed to represent a corps-size force, too? Are they very vulnerable to infantry if they are just sitting there on their own?